.Buildings.Applications.DataCenters.DXCooled.Controls.CoolingMode

Information

This model implements a cooling mode controller for an air-cooled direct expansion (DX) cooling system with an airside economizer. This controller is based on a simplified differential dry-bulb temperature control strategy, as described in ASHRAE G36.

There are three cooling modes for this system: free cooling (FC) mode, partially mechanical cooling (PMC) mode and fully mechanical cooling (FMC) mode. The detailed switching logic is shown in the following:

The airside economizer is enabled when:

• T_out<T_ret

The airside economizer is disabled when:

• T_out>T_ret

The DX coil is enabled when:

• T_out>T_sup,set

The DX coil is disabled when:

• T_out>T_sup,set

where T_swi is the switching temperature, subscript set means set point, out means outdoor air, ret means return air, and sup means supply air. A deadband δT can be added to the above logics to avoid frequent switching.

Revisions

• August 16, 2017 by Yangyang Fu:
  First implementation.